1. Field of the Invention
This invention relates to a carbon rod assembly for arc gouging and blasting of a metallic article, and more particularly to a carbon rod assembly having similarly shaped first and second carbon rod pieces connected to each other for arc gouging and blasting of a metallic article.
2. Description of the Prior Art
Heretofore, arc gouging and blasting of a metallic article such as a steel article has been carried out by establishing an electric arc between a carbon rod held by a holder with an air jetting nozzle and a metallic workpiece surface, so as to melt the metal surface of the workpiece by the arc and to blow off the thus molten metal by compressed air ejected from the air jetting nozzle. This method of arc gouging and blasting of the prior art has a shortcoming in that the high temperature of the electric arc requires a certain clearance kept between the holder and the workpiece, so that stub portions of the carbon rods corresponding to about 20% of the new carbon rods are discarded and wasted to keep the thus required clearance.
To mitigate the waste of the carbon rods, it has been proposed to connect the carbon rods with a metallic sleeve or a carbonaceous nipple or to connect them by forming a projection and a recess at opposite ends of each carbon rod so as to facilitate the joining of adjacent carbon rods by inserting the projection of one carbon rod into the recess of the adjacent carbon rod with or without adhesive applied thereto. Such proposals of connection of adjacent carbon rods have shortcomings in that extra parts for connection, e.g., sleeves or nipples are necessary at the job site, that formation of the projections and recesses and the application of the adhesive are time-consuming and costly, and that the connected portions are susceptible to deformation due to heat generated thereat, which deformation tends to hamper the establishment of stable arc for gouging and blasting.